Heat supply to low-energy buildings in district heating areas: Analyses of CO2 emissions and electricity supply security

In several housing development projects in Norway the requirements related to the mandatory connection to district heating plants have shown to be a barrier for building low-energy residential buildings. The developers have considered the costs related to both low-energy measures and a space heating system that can utilize district heat to be too high to give the project acceptable profitability. In these projects the developers wanted to use a cheaper electric space heating system. Based on models representative for the range of the Norwegian district heating plants, calculations show that the CO₂ emissions related to heating in residential buildings with an energy standard in accordance with the new building regulations and that are connected to the district heating grid, are lower than for similar buildings with a low-energy standard and with heating based on electricity. However, in a long term perspective the differences are marginal when considering the national annual CO₂ emissions. Similarly, increased peak power demand due to electricity-based heating may also be regarded as marginal when compared to the present maximum peak power capacity in Norway.     

Analysis and optimization of the use of CHP-ORC systems for small commercial buildings

The use of combined heating and power (CHP) systems is increasing rapidly due to their high potential of reducing primary energy consumption (PEC), cost, and carbon dioxide emissions (CDE). These reductions are mainly due to capturing the exhaust heat to satisfy the thermal demand of a building. However, when the CHP system is operated following the electric load, the recovered exhaust heat may or may not be sufficient to satisfy the thermal demand of the facility. When the recovered exhaust heat is more than the heat required, the excess is usually discarded to the atmosphere. An organic rankine cycle (ORC) can be used to recover the surplus exhaust heat to generate extra electricity. Therefore, combining the ORC system with the CHP system (CHP-ORC) reduces the electricity that has to be produced by the CHP system, thereby reducing the total PEC, cost, and CDE. The objective of this paper is to study the energetic, economical, and environmental performance of a combined CHP-ORC system and compare its performance to a standalone CHP system and a reference building for different climate zones. A comparison of a CHP-ORC system operating 24 h with a system operating during typical office hours is also performed.     

Optimum, technical and energy efficiency design of residential building in Mediterranean region

Jordan heavily relies on imported oil and gas for meeting its energy need as the same time the construction sector consumed more than half of the total electricity consumption in Jordan in 2008. In order to provide the occupants with thermal comfort at least cost, applying energy saving measures into early design stage can be significant to achieve this goal.This paper discusses an assessment of best orientation of the building, windows size, thermal insulation thickness from energetic, economic and environmental point of view for typical residential building located in Mediterranean region. The results show that about 27.59% of annual energy consumption can be saved by choosing best orientation, optimum size of windows and shading device, and optimum insulation thickness. The Life Cycle Cost (LCC) is reduced by 11.94%. The specific energy consumption per square meter is 64 kWh/m² a.     

寒冷地区公共建筑节能模拟分析

公共建筑相对于居住建筑来说是耗能大户,降低公共建筑的能耗水平就显得至关重要.结合大连市实际新建公共建筑,利用建筑能耗模拟软件PBECA2008,对寒冷地区公共建筑进行能耗分析并进行优化分析.分别从建筑地面保温,外窗传热系数、外墙保、屋顶保温4个方面进行分析研究,分析这些因素的变化时公共建筑节能率的影响程度,找到对公共建筑物能耗影响较大的因素.为既有建筑节能改造工作提供重点改进的方向,从而提出公共建筑节能设计建议.     

生物炭混凝土生命周期CO2排放评价

为评价生物炭混凝土的CO₂排放量,采用生命周期评价技术构建了生物质热解生产生物炭过程的碳排放计算模型、生物炭混凝土从原材料生产到混凝土拆除废弃阶段CO₂排放量化模型和生物炭混凝土服役期碳化-吸收模型,同时研究了生物炭按质量比例取代水泥对混凝土力学性能的影响。在此基础上,计算了1 m³C30生物炭混凝土的CO₂排放量,并与普通C30混凝土CO₂排放量进行对比。结果表明:生物炭作为一种碳负性材料,其碳元素含量越高,CO₂减排效果越好; 当生物炭取代率小于5.0%时,研磨后的超细炭颗粒可以充分发挥填充和内固化效应,有效地提高混凝土的力学性能; 生物炭混凝土生命周期CO₂排放量随生物炭取代率的提高而降低,5%取代率的1 m³木屑生物炭混凝土相比普通C30混凝土,可减排CO₂66.5 kg,减排率为20.7%; 生物炭混凝土在服役期内因碳化吸收CO₂占总碳排放量的1.8%～2.5%,而拆除废弃阶段由于混凝土的比表面积呈指数增长,碳化吸收量需要进一步研究。     

夏热冬冷地区居住建筑节能窗传热系数和遮阳系数优化研究

居住建筑的围护结构中,门窗的保温隔热性能最差,是影响室内热环境质量和建筑节能的主要因素之一,提高其保温隔热性能可显著降低建筑能耗。本文以夏热冬冷地区典型城市南京为例．选择最具代表性的三类居住建筑为研究对象,通过DeST-h模拟软件,探讨不同居住建筑外窗的最佳传热系数和遮阳系数,旨在为建筑师和开发商在选用节能窗产品的过程中,提供较为切实可行、直观明了的参考依据。     

Economic and environmental evaluation of micro CHP systems with different operating modes for residential buildings in Japan

The growing worldwide demand for less polluting forms of energy has led to a renewed interest in the use of micro combined heat and power (CHP) technologies in the residential sector. The operation of micro CHP system results in simultaneous production of heat and power in a single household based on small energy conversion units. The heat produced may be used for space and water heating and possibly for cooling load if combined with an absorption chiller, the electricity is used within the house.In this paper, two typical micro CHP alternatives, namely, gas engine and fuel cell for residential buildings, are analyzed. For each facility, two different operating modes including minimum-cost operation and minimum-emission operation are taken into consideration by employing a plan and evaluation model for residential micro CHP systems. The analysis results show that the fuel cell system is recognized as a better option for the examined residential building from both economic and environmental points of view. With the operation considering optimal economic benefits, annual energy cost is reduced by about 26%. On the other hand, while maximizing the environmental merits, annual CO₂ emissions are reduced by about 9%.     

Energy-efficient virtual sensor-based deep reinforcement learning control of indoor CO2 in a kindergarten

High concentrations of indoor CO₂ pose severe health risks to building occupants. Often, mechanical equipment is used to provide sufficient ventilation as a remedy to high indoor CO₂ concentrations. However, such equipment consumes large amounts of energy, substantially increasing building energy consumption. In the end, the issue becomes an optimization problem that revolves around maintaining CO₂ levels below a certain threshold while utilizing the minimum amount of energy possible. To that end, we propose an intelligent approach that consists of a supervised learning-based virtual sensor that interacts with a deep reinforcement learning (DRL)-based control to efficiently control indoor CO₂ while utilizing the minimum amount of energy possible. The data used to train and test the DRL agent is based on a 3-month field experiment conducted at a kindergarten equipped with a heat recovery ventilator. The results show that, unlike the manual control initially employed at the kindergarten, the DRL agent could always maintain the CO₂ concentrations below sufficient levels. Furthermore, a 58% reduction in the energy consumption of the ventilator under the DRL control compared to the manual control was estimated. The demonstrated approach illustrates the potential leveraging of Internet of Things and machine learning algorithms to create comfortable and healthy indoor environments with minimal energy requirements.     

LNG富氧燃烧电厂[火用]及[火用]经济分析

利用[火用]及[火用]经济分析方法,应用Aspen Plus模拟软件定量研究H_(2)O和CO_(2)作为稀释剂时对LNG富氧燃烧系统(O_(2)/H_(2)O燃烧系统和O_(2)/CO_(2)燃烧系统)的能耗及经济性的影响。结果表明:O_(2)/CO_(2)燃烧系统的总[火用]效率为51.12%,高于O_(2)/H_(2)O燃烧系统的36.35%;O_(2)/CO_(2)燃烧系统可避免[火用]损率为19.97%,远高于O_(2)/H_(2)O燃烧系统的11.99%。从系统整体而言,在保持系统进料及燃烧条件相同的条件下,O_(2)/CO_(2)燃烧系统[火用]效率更高,从能耗角度来讲,CO_(2)更适合作为LNG富氧燃烧系统的稀释剂,以CO_(2)作为稀释剂可以提高富氧燃烧系统各个组件的优化潜力。     

既有居住建筑围护结构节能改造技术经济性分析

该文采用建筑能耗模拟软件DeST—h,以宁波地区为例,对既有居住建筑围护结构各项节能改造技术进行经济性分析。分析结果表明：塑钢普通中空玻璃窗性价比最高;外墙无论是采用保温砂浆类还是聚苯板类,保温层越厚性价比越低;屋顶保温层越厚性价比越高,但保温层厚度超过40mm后,性价比几乎不变。     

煤矿建筑节能减排改造措施研究及效果分析

基于绿色环保的社会发展背景,以煤矿建筑为研究对象,选择山西运城某煤矿办公楼为研究示例,借助建筑能耗建设软件Doe-2进行热工变量计算,分析重点改造的热工变量,并提出相应的改造措施。从各项改造措施来看,采用发泡聚丙烯隔热材料涂抹外墙、在屋顶增设隔热层并铺设胶粉聚苯颗粒隔热保温浆料这两项措施的节能减排效果最为明显。从综合措施效果来看,示例建筑的年能耗由697 965 kW·h/a下降至419 978 kW·h/a,降幅达到39.83%,年CO_2排放量由10 588 kg/a下降至5 337 kg/a,下降幅度达到49.59%,效果十分显著。     

Concentration variations of pollutants in a work week period of an office

Indoor air quality problems for a typical office space were investigated. Continuous monitoring of concentrations was carried out for CO₂, CO, formaldehyde, and total hydrocarbons. It was found that the CO₂ concentration was at times above 2000 ppm and that for CO above 14 ppm. In addition, concentration levels of formaldehyde and total hydrocarbon were found to peak at midnight and indicated non-human sources. Partial opening of windows resulted in CO₂ concentration levels of 800 ppm or below. Ventilation rate measurements using trace gas decay method found that the air change rates were well below one air change per hour.     

二氧化碳封存技术研究进展

CO₂作为最重要的温室气体越来越受关注,而CCS技术因在大规模减少温室气体排放方面的潜力也受到广泛重视。在广泛搜集国内外有关CCS技术相关资料的基础上,详细介绍了最新的CCS技术现状,列出了国内外最新CCS工程案例,讨论了地质封存、CO₂-EOR、CO₂-ECBM技术的内涵及研究进展,对深部咸水层、枯竭油(气)田、玄武岩含水层、CO₂-EOR及CO₂-ECBM封存技术选型、CO₂泄露、储存容量和可注入性、试验与模拟技术以及选址与风险评估等研究现状进行了讨论并指出了下一步的研究重点。最后,对中国的CCS技术发展进行了展望。     

节能50%的住宅建筑设计

吉林市节能建筑试点工程采用膨胀珍珠岩芯板，外墙内保温作法，并对易出现热桥的外节点部位和屋面，地面，门窗进行保温处理，可取得节能５０％的。     

Performance assessment of fuel cell micro-cogeneration systems for residential buildings

The reduction of greenhouse gas emissions in the building sector to a sustainable level will require tremendous efforts to increase both energy efficiency and the share of renewable energies. Apart from the lowering of energy demand through better insulation and fenestration, small combined heat and power (micro-cogeneration) systems may help improve the situation on the supply side by cutting both the non-renewable energy demand for residential buildings and peak loads in the electric grid. Though still on the brink of market entry, fuel cells are the focus of interest as the prime technology for such systems. In this study, a methodology for assessing the performance of such systems in terms of primary energy demand and the CO₂ emissions by transient computer simulations is established, and demonstrated for a natural gas driven solid oxide fuel cell (SOFC) and, to a lesser extend, a polymer electrolyte fuel cell (PEFC) home fuel cell cogeneration system. The systems were evaluated for different grid electricity generation mix types and compared to traditional gas boiler systems. The interaction with hot water storage and solar thermal collectors, and the impact of storage size and predictive control was analyzed. Typical heat and electricity demand load profiles for different types of residential buildings and occupancy were considered, and the sizing of the fuel cell system in relation to the heat demand of the building was analyzed. Primary energy savings decline for cases with lower heat demand and for cases with solar thermal systems, and peak for fuel cell systems sized in accordance with the heat demand of the building. Future assessments of fuel cell systems will need a refined methodology, and depend on realistic performance characteristics and models that accurately consider dynamic conditions.     

European residential buildings and empirical assessment of the Hellenic building stock,energy consumption,emissions and potential energy savings

The existing building stock in European countries accounts for over 40% of final energy consumption in the European Union (EU) member states, of which residential use represents 63% of total energy consumption in the buildings sector. Consequently, an increase of building energy performance can constitute an important instrument in the efforts to alleviate the EU energy import dependency (currently at about 48%) and comply with the Kyoto Protocol to reduce carbon dioxide emissions. This is also in accordance to the European Directive (EPBD 2002/91/EC) on the energy performance of buildings, which is currently under consideration in all EU member states. This paper presents an overview of the EU residential building stock and focuses on the Hellenic buildings. It elaborates the methodology used to determine the priorities for energy conservation measures (ECMs) in Hellenic residential buildings to reduce the environmental impact from CO₂ emissions, through the implementation of a realistic and effective national action plan. A major obstacle that had to overcome was the need to make suitable assumptions for missing detailed primary data. Accordingly, a qualitative and quantitative assessment of scattered national data resulted to a realistic assessment of the existing residential building stock and energy consumption. This is the first time that this kind of aggregate data is presented on a national level. Different energy conservation scenarios and their impact on the reduction of CO₂ emissions were evaluated. Accordingly, the most effective ECMs are the insulation of external walls (33–60% energy savings), weather proofing of openings (16–21%), the installation of double-glazed windows (14–20%), the regular maintenance of central heating boilers (10–12%), and the installation of solar collectors for sanitary hot water production (50–80%).     

夏热冬冷地区小城镇住宅门窗节能技术措施

门窗是小城镇建筑绝热的薄弱环节,随着门窗面积不断扩大,建筑能耗也不断增加,因此,门窗的节能研究对改善住宅室内热环境具有非常重要的意义。从门窗节能的重要性入手,分析了门窗能量损失的方式,提出了夏热冬冷地区小城镇住宅门窗节能的技术措施。     

长江流域居住建筑围护结构隔热保温问题

针对长江流域居住建筑围护结构保温隔热措施的必要性,总结出对建筑围护结构进行保温隔热的优点,阐述了围护结构的几种保温形式及保温隔热性能的衡量指标,实测结果表明保温措施对实现该地区的节能目标具有重要作用。     

ECOTECT能耗模拟下既有住宅建筑围护结构节能改造的热环境分析研究

目前,既有住宅建筑节能改造主要有围护结构改造和供热计量改造两方面。围护结构节能改造主要包括:外墙节能改造、外窗节能改造、屋面节能改造等技术措施的研究;建筑物围护结构节能改造除了能够降低建筑能耗之外,对建筑物室内热环境也有很大影响。采用ECOTECT能耗模拟软件,对西安市某住宅建筑围护结构不同节能改造方案的热环境进行模拟,深入分析不同节能改造方案的能源消耗、不舒适度、围护结构得热、温度分布和热舒适度情况,以热舒适为前提、节能为目的选择最优的节能改造方案。为既有住宅建筑节能改造方案优选提供依据。     

浅析建筑物节能和空调节能

对建筑物节能,空调节能做了初步探究,并对二者的关系进行了分析,浅析了建筑物节能,空调节能的现状及可行做法,例如,建筑物朝向、形状,建筑物围护结构的保温隔热性能,窗户隔热及建筑遮阳,室内设计参数,等等.